Fish Physiology and Biochemistry 22: 191–197, 2000. © 2000 Kluwer Academic Publishers. Printed in the Netherlands. 191 A new technique of feeding, repeated sampling of blood and continuous collection of urine in white sturgeon D. F. Deng 1 , S. Refstie 2 , G.-I. Hemre 3 , C. E. Crocker 4,∗ , H. Y. Chen 5 , J. J. Cech Jr. 4 and S.S.O. Hung 1,∗∗ 1 Department of Animal Science and 4 Department of Wildlife, Fish and Conservation Biology, University of Cali- fornia, One Shields Ave., Davis, CA 95616, USA; 2 AKVAFORSK (Institute of Aquaculture Research AS), N-6600 Sunndalsøra, Norway; 3 Institute of Nutrition, Directorate of Fisheries, N-5035 Bergen, Norway; 5 Institute of Marine Biology, National Sun Yat-Sen University, Kaohsiung, Taiwan; ∗ Present address: Department of Molec- ular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI 02912, USA; ∗∗ Author for correspondence (Phone(530) 752-3580; Fax(530) 752-0175; E-mail: sshung@ucdavis.edu) Accepted: August 20, 1999 Key words: cannulation, intubation, urinary catheterization Abstract A new technique combining oesophageal intubation, dorsal aorta cannulation, and urinary catheterization was developed to monitor concentration of nutrients in the blood circulation and their metabolites in the urine of 1–2 kg white sturgeon, Acipenser transmontanus. Three experiments were conducted to assess the technique based on: (1) quantitative delivery of nutrients; (2) stress levels post-operation; and (3) monitoring of nutrients in the blood and metabolites in the urine. In Experiment 1, recovery of intubated Cr 2 O 3 was 105 ± 5% (mean ± SEM, n = 3) 3 h after intubation. In Experiment 2, plasma cortisol and glucose concentrations returned to respective basal levels of 8.2 ± 1.8 ng ml −1 and 74 ± 8 mg dl −1 (n = 9) 48 h post-operation. In Experiment 3, sturgeon intubated with 1 g kg −1 body weight of glucose or dextrin at 48 h post-operation showed a significantly different (p< 0.05) peak plasma glucose level of 139 ± 4 and 100 ± 5 mg dl −1 (n = 5), respectively, at 4 h. Urinary glucose excretion was 1.8 ± 0.9 mg kg −1 h −1 (n = 5) 4–8 h after intubation with glucose. Our results show that the new technique allows quantitative delivery of nutrients, repeated sampling of blood, and continuous collection of urine in white sturgeon with minimum stress. Introduction Investigations of nutrient absorption and assimilation in fish following oral administration have focused on regulation of glucose (Phillips et al. 1948; Shimeno et al. 1977; Furuichi and Yone 1981; Wilson and Poe 1987; Hung 1991) and amino acids (Yamada et al. 1981; Murai et al. 1987; Murai and Ogata 1990; Ng et al. 1996; Schuhmacher et al. 1997). The method used in these experiments combined force- feeding with subsequent blood withdrawal by needles and syringes in the netted and anaesthetised fish. This method, however, has three major limitations. Firstly, the handling associated with the method is stressful. The stress response in fish includes elevated blood glucose levels secondary to release of cate- cholamines and cortisol (Gamperl et al. 1994). When applying the method to address carbohydrate tolerance or amino acid utilization in fish, the results may be confounded with the stress response. Secondly, the method does not allow repeated sampling on the same individual fish, thus requiring large numbers of fish and tanks. This results in large variations in the mea- surements due to the large variations among different animals and tanks. This in term results in lower sta- tistical power to detect differences among treatments (Hung 1989). Finally, the method does not allow the assessment of urinary excretion of glucose and other metabolites.